UTAU should play your voicebanks...maybe you didn't do it right? Here's a brief list of how to make it work with your UTAU. (It's pretty self-explanatory.) This is for PC UTAU, so IDK if UTAU-Synth works the same. This is also for UTAU ver. 4.18.
1. Record. (Obviously)
2. You should have made a file folder for your UTAU's voice files. Name it the same name as your UTAU.
3. Put the voice samples inside the folder (Along with the oto, readme, art, ect.)
4. Put your UTAU's folder into the folder where you keep your banks.
5. Open UTAU.
6. Go to the 'tools' tab. (The second closest to the right; the 7th tab.)
7. Go down to 'options'. (It's the last one)
8. This thing will pop up that says 'option' if you're using UTAU in English.
9. click the tab that says 'bank regist.' (its the third from the left)
10. A thing should come up where you enter the UTAU's name and the location it's in on your PC. Type your UTAU's name in the shorter box that says 'Name'.
11. There should be a longer box, and next to it there should be a little button that says 'select...'. Click that.
12. It will bring up your file explorer. Go to the folder your voicebank is saved in.
13. Double click on your voicebank.
14. Click on the first file in the bank (IT HAS TO BE A SOUND FILE. It can't be the art or oto or something. A breath file will work.)
15. After you've selected the sound, click 'open' at the bottom of your file explorer. (it will be next to the cancel button, and under the file name and type.)
16. Once you do that, it will input where your UTAU is and the name of the UTAU if you didnt input it earlier.
17. Across from the box that says 'name', it will have 3 buttons. These buttons say 'Add', 'set', and 'delete' in order from right to left. You want to click the one that says 'add.'
18. Click 'Ok' at the bottom. (DO NOT EXIT OUT WITHOUT CLICKING OK OR IT WON'T SAVE THE BANK INTO UTAU. You will have to do steps 6-18 AGAIN if you do this.)
19. You can close the 'option' thingy as long as you clicked 'ok'.
20. If you want to use your UTAU at that moment, go to the 'Project' tab. It's the 4th from the right.
21. Click the bottom option that says 'project property.'
22. A menu that says 'project property' should come up.
23. There should be a part that says 'Voice Bank'. The default voice should be set as Defoko/Uta. Above the thing that says 'voice uta' there should be a box with a little black upside down triangle. It should say 'info' next to the box.
24. Click the black triangle. A drop-down menu will appear.
25. Scroll until you see your UTAU's name. (If you don't have a whole bunch of banks, you won't have to scroll.)
26. Click your UTAU's name. Underneath the name, there will be a box that shows the location of the voicebank in your PC. Underneath THAT there should be a rectangular utton that says 'OK'. Click it.
27. Now your UTAU is ready to sing! What I always do is check to see if it's working. Just put 'a e i o u' in, then select the notes and push play. you should hear your UTAU sing 'a e i o u'. If that doesn't work, try repeating steps 6-26 again. Also, set your compter's locale to japanese. UTAU will function better, and the text that is in 'gibberish', officially called 'mojibake' will become japanese characters. If you aren't sure how to change your locale, here's a link with instructions on how to do it (it's really easy) http://windows.microsoft.com/en-us/windows/change-system-locale#1TC=windows-7
I hope I helped! If you'e still having problems, I would recommend speaking to a more experienced UTAU user and see if they can help you.
By the way, here is a link to Ritsu's VBs. http://canon-voice.com/normal.html
To get the CV VB, make sure you click the one that says 'Normal CV Voicebank ver 1.5.1 alone sound.'
If you want to download some VBs, go on UTAU wikia. (http://utau.wikia.com) It's where I get all my VBs from.
Teto is also a good Japanese VB to start with.